The present invention refers as a new industrial product to a fibrous product which contains cellulosic fibres and can replace asbestos. It refers likewise to the method of preparation and the use of the said fibrous product, in particular in the field of covering panels. It is aimed in particular at the obtaining of a support comprising cellulosic fibres associated if the occasion arises, with non-cellulosic fibres, having good dimensional and thermal stability, resistance to water and the humidity in the air and intended in particular to replace asbestos in the production of coverings such as ground coverings or "cushion floor" which are designed starting from an asbestos sole.
It is known that the employment of asbestos implies
(i) recourse to complicated installations bringing about considerable investment and operational expenses, and PA1 (ii) respect for very strict rules of safety and hygiene in order to avoid any risk of absorbtion or inhalation of asbestos fibres and dust. PA1 (a) slightly refined cellulosic fibres having a Schopper-Riegler degree lying between 15 and 35, in association if the occasion arises, with other fibres, PA1 (b) at least one flocculating agent, PA1 (c) at least one binder, and PA1 (d) at least one mineral filler and if the occasion arises, other additives arising in the paper industry, such as retention agents, pH- regulating agents, dry state resistance agents, colorants and antibiotic substances. PA1 (a) slightly refined cellulosic fibres having a Schopper-Riegler degree lying between 15 and 35, in association if the occasion arises, with non-cellulosic fibres, PA1 (b) at least one flocculating agent, PA1 (c) at least one binder, and PA1 (d) at least one mineral filler, in order to obtain the cellulosic product in the form of a sheet; and, if necessary: PA1 (e) at least one sizing agent (in order to reduce the absorbtion of water by the fibres) such, in particular, as the anhydrides of dicarboxylic acids, the dimeric alkylketenes and paraffin emulsions (advantageously 0.1 to 2 parts by weight of at least one sizing agent will be employed per 100 parts by weight of fibres (a)); PA1 (f) at least one retention agent chosen from the group consisting of: PA1 (g) at least one lubrication agent, the preferred lubrication agents from Stage (1) in accordance with the invention being fatty acid derivatives so as to favour anti-adherance of the resulting sheet to the wet presses, the felts and the dryer cylinders; and if the occasion arises, PA1 (h) other additives such, in particular, as one or more agents for resistance to the dry state such as cold-soluble starch, alginates, mannogalactans and galactomannan ethers, and one or more colorants (those suitable, in particular, according to need, are the acid, basic or direct colorants). PA1 (.alpha.) a sizing agent of Points (e) and (f) at the rate of 5 to 10 parts by weight of the said sizing agent per 100 parts by weight of latex (amongst the sizing agents which are suitable here may be mentioned the dimeric alkylketenes and paraffin emulsions); PA1 (.beta.) an anti-foaming agent at the rate of 0.1 to 0.3 part by weight per 100 parts by weight of latex; PA1 (.gamma.) a lubricating agent at the rate of 0.5 to 2 parts by weight of the said agent per 100 parts by weight of latex, the lubricating agent preferred being here ammonium stearate which gives better results than the metallic stearates (Ca and Mg); and PA1 (.delta.) at least one antibiotic substance chosen from the group consisting of the bactericides and the fungicides; advantageously two antibiotics will be employed, one acting mainly as bactericide and the other as fungicide, the preferred proportions of each antibiotic substance being 1500 to 2500 ppm by weight with respect to the weight of the sheet obtained in Stage (1) and, in particular, 1500 to 2500 ppm of bactericide and 1500 to 2500 ppm of fungicide.
It is likewise known that if asbestos supports exhibit good properties of dimensional and thermal stability and inputrescibility they do not possess good mechanical properties because they have poor internal cohesion and poor resistance to traction and to tearing.
It is likewise known that it has been proposed to replace asbestos by a fabric comprising cotton and glass wool fibres. Such a fabric displays the disadvantage of being much too stiff.
In order to solve the technical problem of replacement of asbestos a solution is proposed in accordance with the invention, which is different from that of the prior mixture of cotton and glass wool and which calls upon techniques which are purely those of papermaking. Thus the technical solution in accordance with the invention uses conventional papermaking means of manufacture and coating such as flat or inclined or vertical table machines, size-presses, master scrapers, air blades, trailing blades, or rolled coaters and mechanical means such as refining, pressing, and if the occasion arises, smoothing.